Ab initio calculations for the effect of wet oxidation condition on the reaction mechanism at 4H-SiC/SiO2 interface

The reaction of a O-2 molecule coexisting with wet oxidants such as a H2O molecule and OH groups at the 4H-SiC/SiO2 interface is investigated by performing ab initio calculations. Our calculations demonstrate characteristic features of the reaction depending on the wet oxidation condition. We find several possible reactions of oxidants different from those of O-2 and H2O molecules obtained by previous calculations. On the Si-face, a H2O molecule and single OH group hardly contribute to the reaction at the interface, which results in the formation of a CO molecule from the dissociation of the O-2 molecule. In contrast, a CO2 molecule is formed in the SiO2 region after the reaction of both O-2 and H2O molecules on the C-face. We also find that the reaction of O-2 accompanied by a wet oxidant is more thermally activate than those by O-2 and H2O molecules. These results suggest that the oxidation reactions can be promoted by controlling the wet ambient condition. (C) 2020 The Japan Society of Applied Physics